Epidemiology of multiple chronic conditions


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Epidemiology of multiple chronic conditions

  1. 1. Introduction The aging of mankind, which we are currently witnessing all over the world, is unprecedented in human history. Life expectancy breaks records, and a 100th birthday is no lon-ger a rare event. The reverse side of this – in many respects successful – development is the increasing number of © 2013 The Authors. This is an open-access article and may be freely copied, distributed, transmitted and adapted by anyone provided the original author, citation details and publisher are acknowledged. The work is made available under the Creative Commons Attribution-NonCommercial-ShareAlike License. Published by Swiss Medical Press GmbH | www.swissmedicalpress.com 36 Journal of Comorbidity 2013;3:36–40 Editorial Epidemiology of multiple chronic conditions: an international perspective François G. Schellevis NIVEL (Netherlands Institute for Health Services Research), Utrecht, The Netherlands; Department of General Practice and Elderly Care Medicine/EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands Abstract The epidemiology of multimorbidity, or multiple chronic conditions (MCCs), is one of the research priority areas of the U.S. Department of Health and Human Services (HHS) by its Strategic Framework on MCCs. A conceptual model addressing methodological issues leading to a valid measurement of the prevalence rates of MCCs has been developed and applied in descriptive epidemiological studies. Comparing these results with those from prevalence studies performed earlier and in other countries is hampered by methodological limitations. Therefore, this paper aims to put the size and patterns of MCCs in the USA, as established within the HHS Strategic Framework on MCCs, in perspective of the fi ndings on the prevalence of MCCs in other countries. General common trends can be observed: increasing prevalence rates with increasing age, and multimorbidity being the rule rather than the excep-tion at old age. Most frequent combinations of chronic diseases include the most frequently occurring single chronic diseases. New descriptive epidemiological studies will probably not provide new results; therefore, future descriptive studies should focus on the prevalence rates of MCCs in subpopulations, statistical clustering of chronic conditions, and the development of the prevalence rates of MCCs over time. The fi nding of common trends also indicates the necessary transition to a next phase of MCC research, addressing the quality of care of patients with MCCs from an organizational perspective and with respect to the content of care. Journal of Comorbidity 2013;3:36–40 Keywords: multimorbidity, multiple chronic conditions, prevalence, methodology, quality of care Correspondence: Prof. François Schellevis MD, PhD, NIVEL (Netherlands Institute for Health Services Research), PO Box 1568, 3500 BN, Utrecht, The Netherlands. Tel.: +31 30 2729 653; fax: +31 30 2729 729; E-mail: f.schellevis@nivel.nl Received: Aug 28, 2013; Accepted: Oct 28, 2013; Published: Dec 24, 2013 people with chronic diseases. The occurrence of many chronic diseases is related to increasing age, which can often be explained by long-lasting exposure to risk factors (e.g. smoking, overweight, physically burdensome labor). In 1986, Olshansky and Ault fi rst predicted this develop-ment by announcing the entry into the “Fourth Stage of the Epidemiologic Transition: The Age of Delayed Degen-erative Diseases” [1], calling for “new ways of thinking about aging, disease, morbidity, mortality, and certainly how life will be lived in advanced ages in the very near future.” However, at that time, Olshansky and Ault did not specifi cally predict the increasing number of people with multiple chronic conditions (MCCs), which has received increasing attention over the last few decades, and which
  2. 2. Epidemiology of multiple chronic conditions 37 represents a major challenge for public health, healthcare, and social care as recognized by the U.S. Department of Health and Human Services (HHS) by its Strategic Frame-work on Multiple Chronic Conditions [2]. Although the relevance of MCCs, or comorbidity, was demonstrated by Feinstein back in 1970 [3], the attention to MCCs has only increased in the last decade when healthcare pro-fessionals became aware that many people who visited them daily for the management of their multiple chronic diseases did not resemble the “model” patients with a single chronic disease who were included in the random-ized clinical trials to establish the evidence for effective treatment and management [4]. This also signifi es the end of what one could call the fi rst wave of evidence-based medicine: effective treatments have been established for many chronic diseases; however, the effectiveness of treat-ment has been established in homogeneous single-disease study populations in whom the existence of other chronic conditions is usually an exclusion criterion [5]. Awareness of the relevance of MCCs initially led to the establishment of the size, patterns, and determinants of MCCs by descriptive epidemiological research. Many researchers from all over the world performed such analy-ses [6], often by using existing administrative or clinical databases. In addition, within the HHS Strategic Frame-work on MCCs, analyses have been published recently on the epidemiology of MCCs across different settings in US healthcare [7]. Insight into the size and patterns of MCCs in differ-ent settings is necessary for the development of preventive and management strategies, and for prioritizing studies to establish evidence for effective treatment of patients with MCCs. This paper aims to put the size and patterns of MCCs in the USA, as established within the HHS Strate-gic Framework on MCCs, in perspective of the fi ndings on the prevalence of MCCs in other countries. This broader perspective will provide insight into the general-izability of fi ndings at national levels. MCC prevalence rates Valid comparisons of the prevalence rates of multimor-bidity require a rigorous methodological approach, with unequivocal defi nitions, and inclusion criteria for exist-ing data or strict rules for collection of new data. Several authors have addressed the methodological challenges in providing the MCC prevalence rates to be comparable with other studies. Criteria for comparability of the MCC prevalence rates include commonality in: (1) the defi nition of chronicity; (2) the level at which chronic conditions are defi ned (e.g. transient ischemic attack or cerebrovas-cular disease); (3) the number of chronic conditions under study; (4) the defi nition of multimorbidity; and (5) the © 2013 The Authors study population, healthcare setting, or data source (e.g. administrative data, clinical databases, or population sur-veys) [8–10]. Within the HHS Strategic Framework on MCCs, a conceptual model has been developed which addresses most of these criteria [11]. The two most recent systematic reviews on prevalence studies on multimorbidity [8,9] had to deal with the heterogeneity of the performed studies. The prevalence study performed within the HHS Strategic Framework on MCCs [10] applied their own conceptual model [11]. All of these studies had the defi nition of multimorbidity in common: two or more chronic conditions in the same person. The results of these prevalence studies are summa-rized in Table 1 [8–10,12–29]. This table shows the wide variation in the prevalence rates of multimorbidity as can be expected from heterogeneous data sources. However, there is a clear and consistent trend towards higher preva-lence rates at older age. Moreover, almost all studies show that at advanced age, multimorbidity is the rule rather than the exception. MCC patterns Some studies [e.g. 10], and the study performed within the U.S. HHS Strategic Framework on MCCs [29], have paid attention to the pattern of MCCs, i.e. which chronic conditions often co-occur. These studies all provide the same consistent results, which are highly predictable by the prevalence rates of the most frequently occurring single chronic conditions. The fi ve most prevalent combina-tions of two chronic conditions (“dyads”) usually include hypertension, (osteo)arthritis, ischemic heart disease, diabetes mellitus, with depression and cancer occurring more prominently in dyads of chronic conditions at older age. Although the comparability of studies on patterns of MCCs will highly depend on the level at which chronic conditions are defi ned, this does not seem to affect the patterns of dyads of chronic conditions. Next phase in MCC research These global comparisons between the MCC prevalence rates established in the USA and abroad and the patterns of MCCs led to the conclusion that new descriptive epidemiological studies will probably not provide sig-nifi cantly different results. This does not mean that these types of studies should no longer be undertaken. There are still many valid reasons for continuing in-depth descrip-tive studies, e.g. in specifi c subpopulations, defi ned by sociodemographic (e.g. ethnic, socioeconomic), medical (diseases), or functional (disability) characteristics. Stud-ies into (statistical) clustering of diseases, showing higher Published by Swiss Medical Press GmbH | www.swissmedicalpress.com Journal of Comorbidity 2013;3:36–40
  3. 3. 38 F. G. Schellevis Table 1 Prevalence of multiple chronic conditions (MCCs) from studies included in systematic reviews outside of the USA and a study performed within the U.S. Health and Human Services Strategic Framework on MCCs. Source Country Study population, age Studies cited in Fortin et al., 2012 [8] and/or Marengoni et al., 2011 [9] van den Akker et al., 1998 [12] Netherlands General population, all Britt et al., 2008 [13] Australia General practitioner Cazale and Dimitru, 2008 [14] Canada General population, 12+ 7 12–19: <1% Fuchs et al., 1998 [15] Israel General population, Fortin et al., 2005 [16] Canada Residents, 18+ All diagnoses 65+: 98% Kadam et al., 2007 [17] UK Visitors of general Loza et al., 2009 [18] Spain Living in community, MacLeod et al., 2004 [19] UK General population, 18+ 8 30% Marengoni et al., 2008 [20] Sweden Living in community Menotti et al., 2001 [21] Finland, Minas et al., 2010 [22] Greece Visitors of primary Nagel et al., 2008 [23] Germany General population, Naughton et al., 2006 [24] Ireland General population, all Rapoport et al., 2004 [25] Canada General population, 20+ 22 20–39: 11% Schellevis et al., 1993 [26] Netherlands General population, all Schram et al., 2008 [10] Netherlands General population, 55+ Depending on setting: 12–13 Uijen and van de Lisdonk, 2008 [27] Netherlands General population, all Walker, 2007 [28] Australia General population, 20+ All long-lasting conditions 70+: 85% Ward et al., 2013 [29] USA General population, 18+ 10 18–44: 7% (males); prevalence rates of combinations of chronic diseases than can be expected by chance, may provide clues for further exploring etiological factors [30]. Moreover, the develop-ment of MCCs over time needs to be monitored. Such studies will provide clues for preventing or delaying the © 2013 The Authors (years) Number of chronic conditions under study Age (years) and prevalence of MCC ages 335 80+: 74% (males), 80% (females) patients, all ages 18 75+: 83% 20–24: 1% 25–44: 2% 45–64: 15% 65–79: 39% 80+: 49% 75–94 14 65% practitioners, 50+ 185 81% 20+ All diagnoses 20+: 30% and institutions, 78+ All chronic conditions 78+: 55% Netherlands, Italy General population, 65–84, males 7 23% (Finland) 13% (Netherlands) 15% (Italy) health care centers, 14+ All chronic diseases 54–75: 23% 50–75 13 67% ages 9 60% 40–59: 26% 60–79: 55% 80+: 64% ages 5 <65: 0.3% 65+: 3.6% (population setting); 68–83 (listed patients in general practices) 55+: 56–72% ages All chronic diseases 65–74: 30% 75+: 55% 9% (females) 45–64: 33% (males); 35% (females) 65+: 63% (males); 62% (females) occurrence of MCCs, and they will support healthcare planning by demonstrating which patients are in highest need of care. However, we must also acknowledge that the body of knowledge about the epidemiology of MCCs is nowadays Published by Swiss Medical Press GmbH | www.swissmedicalpress.com Journal of Comorbidity 2013;3:36–40
  4. 4. Epidemiology of multiple chronic conditions 39 suffi ciently large to take a next step by initiating studies addressing the quality of care for patients with MCCs. The U.S. HHS Strategic Framework on MCCs took up this challenge by prioritizing research into both the organiza-tion and the content of healthcare for patients with MCCs [2]. Two recently published systematic reviews from out-side the USA showed that there is no evidence for any care intervention to be effective for patients with MCCs [31,32]. This calls for further development and evaluation of, for example, case-management programs or programs involving geriatric expertise. Regarding the content of care, inclusion of patients with MCCs in clinical tri-als should be facilitated, parallel to the development of methodologies to deal with heterogeneity. In addition, the impossibility of developing clinical guidelines for all pos-sible combinations of diseases should be acknowledged, leading to priorities being set. Criteria for priority setting could be the level of potential risks for interactions or contradictions between clinical guidelines for the separate chronic conditions. The development and evaluation of effective care programs for patients with MCCs represents an even bigger challenge because programs will have to be tailored to national healthcare systems regarding both the organization and content of care. References 1 Olshansky SJ, Ault AB. The fourth stage of the epidemiologic transi-tion: the age of delayed degenerative diseases. The Milbank Quarterly 1986;64:355–91. 2 U.S. Department of Health & Human Services. Multiple chronic con-ditions: a strategic framework. Optimum health and quality of life for individuals with multiple chronic conditions. Washington, DC: US Department of Health & Human Services; 2010. Available from: http://www.hhs.gov/ash/initiatives/mcc/mcc_framework.pdf [Last accessed Jul 3, 2013]. 3 Feinstein A. The pre-therapeutic classifi cation of co-morbidity in chronic disease. J Chron Dis 1970;23:455–68. 4 Boyd C, Darer J, Boult C, Fried L, Boult L, Wu A. Clinical practice guidelines and quality of care for older patients with multiple comor-bid disease: Implications for pay for performance. J Am Med Assoc 2005;294:716–24. 5 Starfi eld B. Threads and yarns: weaving the tapestry of comorbidity. Ann Fam Med 2006;4:101–3. 6 International Research Community on Multimorbidity. Publica-tions multimorbidity. Available from: https://www.usherbrooke.ca/ crmcspl/fi leadmin/sites/crmcspl/documents/Publications_on_mul-timorbidity. pdf [Last accessed August 25, 2013]. 7 Centers for Disease Control and Prevention. Prev Chronic Disease 2013;10. Available from: http://www.cdc.gov/pcd/current_issue. htm#Apr [Last accessed Jul 3, 2013]. 8 Fortin M, Stewart M, Poitras M-E, Almirral J, Maddocks H. A system-atic review of prevalence studies on multimorbidity: toward a more uniform methodology. Ann Fam Med 2012;10:142–51. © 2013 The Authors Concluding remarks The aim of this paper was to put the size and patterns of MCCs in the USA, as established within the HHS Strate-gic Framework on MCCs, into perspective of the fi ndings on the prevalence of MCCs in other countries. Although the comparability of descriptive epidemiological studies is hampered by many methodological pitfalls, general trends can be observed in studies performed in populations all over the world: an increasing prevalence of MCCs with age, and MCCs at older age being the rule rather than the exception. Moreover, as can been expected, the highest prevalence rates of combinations of diseases is determined by the prevalence rate levels of the separate diseases. Further descriptive studies should go into more depth, especially by studying MCCs in different subpopulations. These consistent fi ndings call for a next phase in MCC research, focusing on the quality of care for patients with MCCs, both from an organizational perspective and in terms of the content of care. Confl icts of interest The author has no confl ict of interest. Funding None declared. 9 Marengoni A, Angleman S, Melis R, Mangialasche F, Karp A, Gar-men A, et al. Aging with multimorbidity: a systematic review of the literature. Ageing Res Rev 2011;10:430–9. 10 Schram MT, Frijters D, van de Lisdonk EH, Ploemacher J, de Craen AJM, de Waal MWM, et al. Setting and registry characteristics affect the prevalence and nature of multimorbidity in the elderly. J Clin Epidemiol 2008;61:1104–12. 11 Goodman RA, Fosner SF, Huang ES, Parekh AK, Koh HK. Defi ning and measuring chronic conditions: imperatives for research, policy, program, and practice. Prev Chronic Dis 2013;10:E66. 12 van den Akker M, Buntinx F, Metsemakers JF, Roos S, Knottnerus JA. 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